1. Technical Field
The present invention relates to an ink composition, a recording method, and a recorded article.
2. Related Art
Inks containing a water-soluble dye are widely used for ink jet printers, fountain pens and the like. For such an ink, various capabilities are desired. For example, it is desirable that such an ink do not clog nozzles or pen tips, and that can dry rapidly, form sufficiently dense images and be stored stably. Also it is desirable that the color of the images formed by the ink do not change much.
It is considered that ink clogging is caused by solidification of a dye precipitated when water is evaporated from the ink. It is therefore believed that the use of a dye having a high saturation solubility in water, which does not easily precipitate even if its concentration is increased, makes clogging difficult. It is also believed that the degree of clogging can be reduced by increasing the color developability of the dye to relatively reduce the dye content in the ink.
In addition, it is incompatible to achieve an ink that does not easily cause clogging and to achieve an ink that can dry rapidly. In order to ensure a balance between these properties, it is studied that various compounds are mixed in the ink. Furthermore, dye molecules have been designed from the viewpoint of improving the color developability of the dye and the light fastness of the resulting images.
In particular, it is strongly desired to increase the light fastness of images formed using an ink containing a yellow dye. For example, JP-A-2008-297541 proposes an ink jet ink containing two yellow dyes, one of which has a pH-buffering ability. This patent document teaches that such an ink can form images superior in light fastness, color developability and hue, and can be stored stably.
JP-A-2004-099725 discloses an ink jet recording ink containing a water-miscible organic solvent and a dye. This patent document teaches that such an ink can be ejected stably without being dried, and can form images superior in hue, light fastness and water fastness. Furthermore, JP-A-2004-091537 discloses an ink jet ink set including a yellow ink containing a dye. This patent document teaches that the yellow ink has a high light fastness and can be ejected stably.
However, the above-mentioned known inks are not necessarily satisfactory in terms of, at least, the difficulty of clogging, the light fastness of the images formed with the inks, and the balance between these properties.
The present inventors found a dye that can impart extremely high light fastness to images, and found that the light fastness and moisture fastness of the resulting image and the difficulty of clogging can be increased by combining the dye and a specific compound.